Universal silicon ring resonator for error-free transmission links

We report the design, fabrication, and characterization of a universal silicon PN junction ring resonator for C band error-free communication links operated up to 50 Gb/s with co-designed optical modulation and detection performance. The universal p-n junction ring device shows co-designed detection responsivity up to 0.84 A/W, in conjunction with a modulation efficiency of -4 V·mm and>8 d B optical modulation extinction ratio, enabling C band 50 Gb/s NRZ communication link with a bit error rate≤3×10^(-12).

High-speed silicon photonic electro-optic Kerr modulation

Silicon-based electro-optic modulators contribute to easing the integration of high-speed and low-power consumption circuits for classical optical communications and data computations.Beyond the plasma dispersion modulation,an alternative solution in silicon is to exploit the DC Kerr effect,which generates an equivalent linear electro-optical effect enabled by applying a large DC electric field.Although some theoretical and experimental studies have shown its existence in silicon,limited contributions relative to plasma dispersion have been achieved in high-speed modulation so far.This paper presents high-speed optical modulation based on the DC Kerr effect in silicon PIN waveguides.The contributions of both plasma dispersion and Kerr effects have been analyzed in different waveguide configurations,and we demonstrated that the Kerr induced modulation is dominant when a high external DC electric field is applied in PIN waveguides.High-speed optical modulation response is analyzed,and eye diagrams up to 80 Gbit/s in NRZ format are obtained under a d.c.voltage of 30 V.This work paves the way to exploit the Kerr effect to generate high-speed Pockels-like optical modulation.

Apodized silicon photonic grating couplers for mode-order conversion

An out-of-plane silicon grating coupler capable of mode-order conversion at the chip–fiber interface is designed and fabricated. Optimization of the structure is performed through finite-difference time-domain simulations,and the final device is characterized through far-field profile and transmission measurements. A coupling loss of 3.1 dB to a commercial two-mode fiber is measured for a single TE0→ LP11 mode conversion grating, which includes a conversion penalty of 1.3 dB. Far-field patterns of the excited LP11 mode profile are also reported.

All-silicon carrier accumulation modulator based on a lateral metal-oxide-semiconductor capacitor

In silicon photonics, the carrier depletion scheme has been the most commonly used mechanism for demonstrating high-speed electro-optic modulation. However, in terms of phase modulation efficiency, carrieraccumulation-based devices potentially offer almost an order of magnitude improvement over those based on carrier depletion. Previously reported accumulation modulator designs only considered vertical metal-oxidesemiconductor(MOS) capacitors, which imposes serious restrictions on the design flexibility and integratability with other photonic components. In this work, for the first time to our knowledge, we report experimental demonstration of an all-silicon accumulation phase modulator based on a lateral MOS capacitor. Using a Mach–Zehnder interferometer modulator with a 500-μm-long phase shifter, we demonstrate high-speed modulation up to 25 Gbit∕s with a modulation efficiency(V_πL_π) of 1.53 V·cm.

Post-fabrication phase trimming of Mach–Zehnder interferometers by laser annealing of germanium implanted waveguides

We demonstrate a novel high-accuracy post-fabrication trimming technique to fine-tune the phase of integrated Mach–Zehnder interferometers, enabling permanent correction of typical fabrication-based phase errors. The effective index change of the optical mode is 0.19 in our measurement, which is approximately an order of magnitude improvement compared to previous work with similar excess optical loss. Our measurement results suggest that a phase accuracy of 0.078 rad was achievable with active feedback control.